Tsutsuji is a transfer student from Onigashima to a junior high school in Tokyo. She has a friendly, open, cheerful personality and is full of curiosity. She is also very determined to improve the image of Oni, but she is a bit timid at first. However, once she decides to do something like this, she has the strength of mind to carry it through. She has a yearning for the city and is especially interested in love and fashion.

Over the centuries, oni (AKA demons of Japanese folklore) got a pretty bad reputation. Now it’s up to three plucky oni kids — sunny Tsutsuji, cool Tsuyukusa and boisterous Himawari — to improve human-oni relations through love, friendship and superpowered underpants!
 
(Source: Sentai Filmworks)
 
Note: Aired in 2 versions, a 60-episode 3-minute short series, and a combined 12-episode 14-minute TV series with the same content. Each episode of the combined version is 5 parts of the original.